/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package cn.edu.thu.laud.objectstore.fieldmanager;

import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.IdentityHashMap;

import org.apache.cassandra.thrift.Cassandra;
import org.apache.cassandra.thrift.Deletion;
import org.datanucleus.ObjectManager;
import org.datanucleus.store.ObjectProvider;

import cn.edu.thu.laud.objectstore.CassandraConsistency;
import cn.edu.thu.laud.objectstore.CassandraManagedConnection;
import cn.edu.thu.laud.objectstore.CassandraStoreManager;
import cn.edu.thu.laud.objectstore.index.BatchMutation;

/**
 * Holds all mutations for the current execution context
 * 
 * @author zhuoan
 * 
 */
public class ObjectManagerDelete extends ObjectManagerMutate {

	//operations of mutations to perform
	//our reference to visited objects so we don't get stuck in a recursive delete
	private IdentityHashMap<ObjectProvider, Object> visited = new IdentityHashMap<ObjectProvider, Object>();
	

	
	public ObjectManagerDelete(ObjectManager om, BatchMutation deletor) {
		super(om, deletor);
	}
	
	/**
	 * Add the deleting if the op hasn't already been visited
	 * @param op The object we're deleting
	 * @param key The key to delete
	 * @param columnFamily The CF to dele
	 * @return True if this is the first visit to the object.  False otherwise
	 */
	public boolean addDeletion(ObjectProvider op, ByteBuffer key, String columnFamily) {
		
		if(visited.containsKey(op)){
			return false;
		}
		
		visited.put(op, null);
		Deletion deletion = new Deletion().setTimestamp(System
				.currentTimeMillis());
		
		mutator.addDeletion(key, Arrays.asList(new String[]{columnFamily}), deletion);
		
		return true;
	}



	public void execute() throws Exception {
		CassandraManagedConnection mcon = (CassandraManagedConnection)om.getStoreManager().getConnection(om);
		Cassandra.Client client = (Cassandra.Client)mcon.getConnection();
		client.set_keyspace(((CassandraStoreManager)om.getStoreManager()).getConnectionInfo().getKeyspace());
		client.batch_mutate(mutator.getMutationMap(), CassandraConsistency.get());
	}
	

}
